1. Field of the Invention
The present invention relates to a large quantity of light type headlamp for use in a vehicle.
2. Related Art
There is a vehicle headlamp for projecting light ahead of the vehicle using a projector type of lamp unit.
Such a projector type of lamp unit serves to forward collect/reflect the light emitted from a light source, arranged in the vicinity on an optical axis extending in a longitudinal direction of the vehicle, toward the optical axis by a reflector, and project the reflected light ahead of the lamp unit through a projection lens arranged in front of the reflector. When a distributed light pattern having a cut-off line on the upper end is formed using this lamp unit, a shade is arranged in the vicinity of the focal point on the rear side of the projection lens and a part of the reflected light from the reflector is cut or shielded to form the cut-off line. (For example, JP-A-05-159603 discloses a vehicle headlamp of this type.)
In recent years, as a vehicle headlamp equipped with the projector type lamp unit, its large quantity of light type thereof has been demanded. Generally, with respect to the light emitted from the light source, reflected by the reflector and incident on the projection lens, the vehicle headlamp equipped with the projector type lamp unit makes effective light projected forward by the projection lens.
However, for example, the light which is incident on the lower side of the reflector and cut by the shade results in the lost light which cannot contribute to distributed light to be projected forward. Further, the light which is not incident on the reflector but goes outward directly from the light source or the light which is incident on the area other than the reflector and makes diffused reflection within the lamp unit results in the lost light which cannot contribute to distributed light. Thus, the general projector type lamp unit makes a large quantity of lost light which cannot contribute to the distributed light to be projected forward. Therefore, effective use of this lost light is demanded.